Silk improved in weight and appearance and process for obtaining the same



ll'o Drawing.

Patentecl May '17, 1932 UNITED AT PA-ranrorrlcs FRIEDRICH W. WEBER, OF HACKENSACK, NEW

JERSEY, ASSIGNOR TO HAYWOOD CHEMICAL WORKS, 013 HAYWOOD, NEW JERSEY, A CORPORATION OF JERSEY arm: IMPROVED m WEIGHT AND APPEARANCE AND raocsss r03 OBTAINING THE I sun I This invention relates to silk improved in weight and appearance, the object of the invention being to provide a process by which said improved silk can be obtained with great regularity, greater convenience and at a lower price; p v

r The art of enhancing the appearance of the inherent brilliancy of the natural silk has to deal with many subtle reactions the effect of whichv isof the greatest .importance for the success of the work." The main principle in weightingpsilk' and increasing its natural lustre is?to:incorporate in the silk, deposits of mineral, salts whichare of absolute whitenessm Disturbing-factors may arise from a variety of sources and as often more than one of such. factors combine in their effect which usually cannot be anticipated, it is extremely hard to? create a process which will give a satisfactory tion.

The process of this present application fully answers all requirements of the art, its principal difference from the process of the application, filed February 2, 1927?, under Serial No. 165,504,0onsists in a partial substitution of the tin-tetrachloride bya soluble zinc result under almost any condisalt in the presence of an acid the calcium salt of which is soluble in Water at the usual temperature. I am aware,= though, that efforts have been made'by the workers in this art to utilize the salts of zinc for the purpose of weighting silk and enhancing its lustre, but the descriptions of these patents disclose the fact that these efforts were bound to be unsatisfactory, thetreated silkdisplaying a dull appearancegand having a coarse touch when tested between the fingers. Moreover, the processes of the prior art were worked under conditions which caused the metal compounds, precipitated in the fiber, at later stages of the process were redissolved to a great extent, thus rendering the operation uncertain and militating against obtainin a definite economical result.

Tn View of the fact that also the efforts of the prior art of weighting silk by means of the insoluble compounds of the rare earth stage (see Heermann, Faerbereiund Tex- Applicatlon filed January 25,1928. Serial No. 249,505.

til-Chemische Julius Springer, Berlin, 1923. pg. 202) the process of the present application is of all the greater importance because it furnishes a product of absolute whiteness and of satis factory increase in Weight.

I have found that the mixture of tin-tetrachloride and of 'a soluble zinc salt, for instance of zinc chloride, zinc sulfate, orany other soluble zinc salt of sufliciently low price to allow its, application, with the addition of a relatively small proportion of an acid capable offorming a calcium salt soluble at ordinary temperature, but not affecting the tin compounds inthe fiber, suchas citric acid, to the mixture of. said salt solutions for the treatment of the silk therewith before solutions of the salts of the rare earth metals act'on the silk, ofi'ers a process for the enhancement of silk which is desirable in all its aspects.

For the better understandin of my new process I. am going to describe y way of example how'I may operate the same; I proceed about as follows:

250 cc. of the usual tin-tetrachloride solution B.) are added to a concentrated solution of 125 gr. of zinc chloride and 5 gr. citric acid in water is then added to the mixture to make 1 liter, the whole presenting an absolutely clear and colorless liquid. If now a skein of silk is treated for one hour in a bath of this liquid, which should be occasionallyagitated during this treatment, and the silk, after the excess of the chloride solution was pressed out, is then treated at C. with a. moderately diluted solution of di-sodium phosphate for 1 hour, the silk has gained as much in weight as if it had been treated with a 31 deg. B. tin tetrachloride solution. This operation is repeated twice.

The silk thus treated now contains the homogeneous mixture of the phosphates of tin and zinc and if it is then treated with solutions of salts of the rare earth metals, such asthe acetates, or the chlorides, the silk absorbs these salts without 'showin any inclination to assume darker shades, The presence of the citric acid in the aforesaid mixture oi tin and zinc chloride solutions is Untersuchungen, publ. by

essential for the reason that it keeps in solution such impurities as lime, magnesia and iron oxide, one of which, if not all, is always present in the industrially applied water and even if such uantities are small, they are sufiicient to do 1 the brilliancy of the silk and to eventually give the same a faint yellow or brownish tint. It is not necessary to have the citric acid present in the subsequent operations because the solutions subsequently applied in the following steps, such as the solution of the di-sodium phosphate, is naturally free of the above mentioned impurities because their phosphates are in-soluble and only a clear solution of the di-sodium phosphate should be applied.

The solutions of the rare earth metal salts are free of these impurities and furthermore, being applied in the form of their acetate and chlorides, would keep lime and magnesia in solution so as to be removed from the silk by the next following step. The excessof these salts of the rare earth metals is then pressed out, the silk washed and then treated once more with sodium diphosphate. Also this operation may be repeated several times. The good effect of the treatment with the mixture of tin tetrachloride and zinc chloride in the presence of citric acid, is also noticed in the further treatmentof silk whichhad already once undergone treatment with solutions of rare earth metals and a solution of soditim-diphosphate, for the capability of the silk to absorb and to thus intermingle quantities of tin-tetrachloride and zinc chloride, respectively the phosphates of tin and zinc, appear just as great as ever.

After the silk has beentreated as described by above example, it is once more introduced into the bath of tin-tetrachloride and zinc chloride; then the excess of said solution is pressed out of it and-after the silk has been washed once more with water, it is finally treated again in a on account of reducing t e opportumtyof a harmful effect to a minimum. Moreover, P

the application of the zinc chloride furnishes the finished product at a lower price not only on account of the lower cost of the chemical, but also on account of the fact that the baths are not discolored and a good increase in weight can be obtained.

Zinc sulfate can also be used in my process because in case calcium compounds should be present in the water, calcium citrate is soluble at ordinary temperature; great precaution, however, is Just the same necessary to keep bathof di-sodi'um phosphate, whereupon it is finished with a solutreating the silk rocess isimportant.

up such conditions as will prevent the formation of insoluble calcium compounds as they would affect the lustre of the silk fiber.

-What I claim is:

1. The process of weighting silk, which comprises treating silk in a mixture of the aqueous solutions of tin tetrachloride and of a zinc salt in the presence of an acid forming a water soluble salt with the alkali earth metals and the iron in the water used as a solvent, treating the silk with a solution of di-sodium phosphate, treating the silk with the solution of a soluble salt of a rare earth metal, treating the silk with a solution of di-sodium phosphate, treating it again with the mixture of the solutions of tin tetrachloride and of a zinc salt, and finally treating the silk again with a solution of di-sodium phosphate.

2. The process comprises treating silk in a mixture of the aqueous solutions of tin tetrachloride and of zinc chloride in the presence of an acid forming a water soluble salt with the alkali earth metals and the iron in the water used as a solvent, treating the silk with a solution of di-sodium phosphate, treating the silk with a solution of a salt of a rareearth'metal, treating the silk with a solution of di-sodium phosphate, washing the silk, treating it again of weighting silk, which with the mixture of a solution of tin tetrasolution of tin tetrachloride and of zinc chloride in the presence of citric acid, treating the silk with a solution of di-sodium phosphate, treating'the silk with a solution of a salt of a rare earth metal and treating the silk with a solution of di-sodium phosphate.

4. The process of weighting silk as described by claim 1, the process comprising in the presence of an organic acid forming with the alkaline earth metal and iron present in the water, a salt soluble in the same at usual temperature and forming also soluble salts with the other metals applied in the process.

5. As a new article of manufacture, silk loaded with a mixture of the phosphates of tin and zinc intermingled with a layer of the hosphate of a rare earth metal.

In witness whereof I have hereunto set my hand.

FRIEDRICH W. WEBER. 

